The invention relates to a changing device for a blowing lance having a blowing tube and a cooling jacket through which coolant can flow and which encloses the blowing tube and whose inlet and outlet are disposed at the end of the blowing lance associated with a coupling head; the coupling head has a receptacle into which said end of the blowing lance can be introduced and which comprises connections for the coolant supply, the coolant discharge and the blowing fluid supply; and the blowing lance can be releasably coupled to the coupling head, while at least the inlet or the outlet of the cooling jacket emerge at a peripheral surface of the blowing lance, the connection associated with the inlet or outlet respectively being disposed on a lateral surface on the receptacle associated with the particular peripheral surface.
Blowing lances are used, for example, to inject oxygen into a converter during the production of steel. The problem of blowing lances inserted in this way is that after a certain period of use they become worn and must be interchanged.
To prevent premature damage to the blowing lance by the high surrounding temperatures in the zone of the converter, the blowing tube, through which the gas injected into the converter passes, is cooled by means of a coolant, usually water. For this purpose the blowing lances normally have a double jacket which encloses two interconnected chambers disposed coaxially with one another and with the blowing tube. The coolant is introduced into the first chamber, immediately adjoining the blowing tube, and then flows along the blowing tube as far as substantially its tip and from that point through the second chamber back to the outlet of the coolant jacket.
For the connection of the blowing fluid, coolant supply and coolant discharge lines, conventional blowing lances have flanges, to which these lines can be connected in conventional manner. When such a blowing lance has to be interchanged, this kind of connection between the supply and discharge lines causes the problem that a considerable time is required for their release and connection. Moreover, in such connections between the supply/discharge lines and the blowing lance, it is impossible to automate the interchange operation. Instead of this, there is the disadvantage that the operation of the blowing lance has to be interrupted for a prolonged period, to prevent danger to the assembling personnel occupied in interchanging the blowing lance.
The time required for the interchanging of the blowing lance can be reduced by means of a device which is disclosed in European Patent Application EP 0 464 427 A2. In that prior art interchangeable device the portion which is provided in the aforedescribed blowing lances for the connection of the supply and discharge lines is associated with a separate coupling head. The coupling head is attached to a frame which also comprises a hydraulic lifting system. The remaining portion of the blowing lance can be so latched into the lifting system that the appropriate end of the blowing lance can be introduced into the receptacle or coupling head. The end opening of the blowing tube and also the inlet and outlet of the cooling jacket are disposed on the end face of the blowing lance. Correspondingly, the connections for the coolant supply and discharge and also the blowing fluid supply are disposed at the end of the coupling head receptacle associated with the end face of the blowing lance.
When the prior art blowing lance is in use, the hydraulic lifting device continuously retains the end face of the blowing lance bearing against the end face of the receptacle, so as to ensure that the blowing tube, coolant inlet and coolant outlet are constantly sealed. At the same time, in view of the considerable pressure at which the coolant and the blowing fluid are introduced into the blowing lance, appreciable pressure forces are required to maintain a hermetic connection.
One device of the kind specified is known from European Patent Application EP 0 441 767 A2. In that device the connections for the coolant supply and discharge of the blowing lance are disposed, together with the connection for the blowing fluid, on a laterally attached plate. The coupling head of this prior art device, by means of which the blowing lance can be releasably coupled, also has a plate on which the connections for the blowing fluid and the coolant are correspondingly disposed. In this prior art device also a hydraulic device is used to press the connections of the coupling head heretically against the connections of the blowing lance.
It is true that the afore-explained prior art interchangeable devices enable a blowing lance to be interchanged within a short time, but they have the disadvantage of requiring expensive hydraulic lifting and pressure-applying devices, which are costly to obtain and maintain, in order to ensure that the blowing lance is permanently and securely hermetically pressed against the connections for the coolant supply and the blowing fluid.
Starting from the afore-explained prior art, it is an object of the invention to provide a changing device for the blowing lance which enables a blowing lance to be rapidly interchanged with low manufacturing and maintenance costs.